U.S. Pat. No. 5,959,715 to Jaffelin disclosed a resilient hinge for spectacle frames. The resilient hinge comprises a male or female knuckle fixed to the end of a frame lug which extends in a direction, and an arm substantially in the extension of the lug and abutting against the lug when the arm is in its normal open position, wherein the inner side of the arm is connected to the knuckle by means of a rigid return device (i.e., a leaf spring) which can rotate freely about the knuckle and operate by bending. The resilient hinge comprises the leaf spring as a resilient element, and the leaf spring is connected to the temple of the eyeglasses through a swivel pin such as in the form of rivet pin.
U.S. Pat. No. 6,336,250 B1 to Kinji et al. disclosed a spring hinge for eyeglasses. The spring hinge comprises a spring member provided on the inside of the temple of the eyeglasses. The spring member is an independent arc-shaped plate with an insertion hole. An intermediate connecting member constitutes the front end portion of the temple and the spring member is installed in a free groove formed by two protrusions.
These hinges employing leaf spring as resilient elements require lots of accessories and have incompact arrangements.